Three-dimensional (3D) type sensing systems are commonly used to generate 3D images of a location for use in various applications. For example, such 3D images are used for creating a safe training environment for military operations or civilian activities; for generating topographical maps; or for surveillance of a location. Such sensing systems typically operate by capturing elevation data associated with the location of the target. One example of a 3D type sensing system is a Light Detection and Ranging (LIDAR) system. The LIDAR type 3D sensing systems generate is data by recording multiple range echoes from a single pulse of light and generating a frame, sometimes referred to as an image frame. Accordingly, each image frame of LIDAR data includes a collection of points in three dimensions (3D point cloud), which correspond to multiple range echoes within a sensor's aperture. These points can be organized into “voxels” which represent values on regular grid in a three dimensional space. Voxels used in 3D imaging are analogous to pixels used in the context of 2D imaging devices. These frames can be processed to reconstruct a 3D image of the location of the target. In this regard, each point in the 3D point cloud has an individual x, y and z value, representing the actual surface within the scene in 3D.
The 3D point cloud as a dataset is composed of spatial measurement of positions in 3D space (x, y, z), where x and y are cross-range spatial positions and z is height. The 3D dataset is generated by systems capable of scanning surfaces, such as stereo paired cameras, radars, laser detection and ranging (LADAR) sensors, etc. This 3D dataset has been used to estimate acceptable landing zones in both civilian and military communities.
Providing information to a pilot landing an aircraft requires an ability to identify safe zones in non-cooperative environments. Non-cooperative environments are zones where there are not enough information about pre-positioned objects, landing area markings, GPS, etc. These sites may also include unknown information about terrain features and obstacles.
A commonly used system in landing zone scenarios includes stereo pair cameras. Stereo pair cameras are capable of estimating range to a landing zone using parallax. Stereo pair cameras have been tested in unmanned aircraft vehicles (UAV) for automatic landing of helicopters in non-cooperative environments.
Current UAV landing zone algorithms are based on what is referred to as a safe landing area determination (SLAD) algorithm, which uses a 3D point cloud dataset to generate a hazard map. The hazard map is used to determine vertical obstacles and landing area slope. The SLAD algorithm searches for locations that pass two key requirements regarding the obstacles and landing area slope. The slope is used to determine values that are larger than a pre-defined slope threshold value. Vertical obstructions are determined by roughness of the terrain, or a hazard map which is based on the absolute value of the hazard map minus the filtered hazard map. The algorithm uses the roughness map to determine regions larger than a pre-defined roughness threshold. Based on these, a map of acceptable regions is created and filtered to avoid regions that are too close to hazards. Finally, the regions are selected by total area available for landing and compared to the aircraft size requirements.
A major drawback of the SLAD algorithm is that it does not provide the landing zone area in real-time. The SLAD algorithm, applied with stereo pair cameras, acquires the information several minutes before the landing process. The UAV then hovers over an area and waits for the landing zone calculation before proceeding with the landing process.
As it will be explained, the present invention advantageously provides real-time visualization of a calculated landing site to the pilot. Using the present invention, the pilot does not have to hover for several minutes above a possible is landing site and, instead, may approach the landing site immediately upon determining that the site is acceptable to the aircraft.